The present invention relates to a synthetic resin crown-shaped retainer for ball bearing, and particularly to a synthetic resin crown-shaped retainer (hereinafter, retainer) as applied to a ball bearing used for devices such as polygon mirrors.
A retainer in relationship with the present invention is used for ball bearings as applied to devices such as polygon mirrors.
The retainer comprises an annulus having an inner peripheral surface, an outer peripheral surface, and plane surfaces formed on both sides thereof perpendicularly with respect to the axis, and a plurality of pockets made up of recesses which are formed at circumferentially spaced intervals on one of the plane surfaces, and a pair of pawls provided at each ends of the pocket and axially projecting from the one of plane surfaces of the annulus. The retainer has basins between the respective pawls, which are greased.
When the ball bearing were rotated, the grease in the basins often passed the pawls to fly out the retainer by the centrifugal force. For this reason, the ball bearing was often subjected to the instantaneous large fluctuations in its speed variations (called in general jitter). In addition, the fluctuations in the speed variations are caused by spacing of clearances to balls from its pawls being increased. The increase in the spacing of the clearance between the respective balls and pawls are of ten caused during the time when a retainer is removed from a metal mold, because the pawls are pulled by force applied to the retainer by the shrinkage stress of the synthetic resin after its formation or production.
The fluctuations in the speed variations affected the performance of the polygon mirror.
Therefore, it is required to prevent grease from being scattered out the basins of the retainer and to restrain the pawls from deforming after being removed from the metal mold.
In order to solve the problems point ed out above, the present invention provides a ball bearing, which includes an inner race, an outer race, a plurality of balls, and a retainer having an annulus, the annulus having annular faces on both sides thereof perpendicularly with respect to the axis, a plurality of pockets made up of recesses which are formed at circumferentially spaced intervals on one of the annular faces, respectively, a pair of pawls provided at both ends of the pocket and axially projecting from one of the annular faces of the annulus so as to prevent the ball from dropping out pockets, and a plurality of plane faces having wells in which grease is kept between the respective pairs of pawls, respectively, wherein the retainer having barriers connected with the back faces of the respective pairs of pawls and circumferentially formed on one of the annular faces, and wherein the pairs of pawls comprise alternate pairs of pawls having each a barrier integrally joined to the respective back faces thereof, and having each a barrier partially joined to the respective back faces thereof.
Each of the barriers are formed along an external edge of the respective plane surface between respectively the back faces of said pawls.